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/*
* hamachi.c
*
* LogMeIn Hamachi
*
* Copyright (C) 2025 - ntop.org
* Copyright (C) 2025 - V.G <v.gavrilov@securitycode.ru>
*
* This file is part of nDPI, an open source deep packet inspection
* library based on the OpenDPI and PACE technology by ipoque GmbH
*
* nDPI is free software: you can redistribute it and/or modify
* it under the terms of the GNU Lesser General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* nDPI is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public License
* along with nDPI. If not, see <http://www.gnu.org/licenses/>.
*
*/
#include "ndpi_protocol_ids.h"
#define NDPI_CURRENT_PROTO NDPI_PROTOCOL_HAMACHI
#include "ndpi_api.h"
#include "ndpi_private.h"
static void ndpi_int_hamachi_add_connection(struct ndpi_detection_module_struct *ndpi_struct,
struct ndpi_flow_struct *flow)
{
NDPI_LOG_INFO(ndpi_struct, "found Hamachi\n");
ndpi_set_detected_protocol(ndpi_struct, flow, NDPI_PROTOCOL_HAMACHI,
NDPI_PROTOCOL_UNKNOWN, NDPI_CONFIDENCE_DPI);
}
static void search_hamachi_tcp(struct ndpi_detection_module_struct* ndpi_struct,
struct ndpi_flow_struct* flow)
{
struct ndpi_packet_struct const * const packet = &ndpi_struct->packet;
NDPI_LOG_DBG(ndpi_struct, "search Hamachi over TCP\n");
if (packet->payload_packet_len > 300 &&
ntohl(get_u_int32_t(packet->payload, 0)) == (u_int32_t)(packet->payload_packet_len-4) &&
ntohl(get_u_int32_t(packet->payload, 12)) == 0x7B7A0DAD)
{
ndpi_int_hamachi_add_connection(ndpi_struct, flow);
return;
}
NDPI_EXCLUDE_DISSECTOR(ndpi_struct, flow);
}
static void search_hamachi_udp(struct ndpi_detection_module_struct* ndpi_struct,
struct ndpi_flow_struct* flow)
{
struct ndpi_packet_struct const * const packet = &ndpi_struct->packet;
NDPI_LOG_DBG(ndpi_struct, "search Hamachi over UDP\n");
/* Skip initial 76-byte handshake (relay mode only) */
if (flow->packet_counter <= 2 && packet->payload_packet_len == 76)
{
if (get_u_int64_t(packet->payload, 0) != 0 ||
get_u_int64_t(packet->payload, 68) != 0)
{
goto exclude_hamachi;
}
return; /* Likely Hamachi handshake */
}
/* Empirically observed minimum */
if (packet->payload_packet_len < 46) {
goto exclude_hamachi;
}
/* Reasonable value for heuristics */
u_int32_t seq = ntohl(get_u_int32_t(packet->payload, 4));
if (seq == 0 || seq > 0xFFFF) {
goto exclude_hamachi;
}
u_int32_t hamachi_l = ntohl(get_u_int32_t(packet->payload, 0));
u_int16_t hamachi_s = ntohs(get_u_int16_t(packet->payload, 8));
if (hamachi_l == 0xFFFFFFFF || hamachi_l == 0)
{
goto exclude_hamachi;
}
u_int8_t dir = packet->packet_direction;
/*
* Hamachi detection logic using 4-stage state machine:
* Stage 0: Initial state, waiting for first packet
* Stage 1: Got packet from dir=0, waiting for dir=1 to complete verification
* Stage 2: Got packet from dir=1, waiting for dir=0 to complete verification
* Stage 3: Both directions verified, protocol identified
*
* Each direction has constant values in bytes 0-3 and 8-9 throughout the session.
* We need to verify consistency within each direction and collect samples from both.
*/
if (flow->l4.udp.hamachi_stage == 0) {
/* Store signature values from first packet and set stage based on direction */
flow->l4.udp.hamachi_long[dir] = hamachi_l;
flow->l4.udp.hamachi_short[dir] = hamachi_s;
flow->l4.udp.hamachi_stage = dir ? 2 : 1; /* Stage 1 for dir=0, stage 2 for dir=1 */
return;
}
if (flow->l4.udp.hamachi_stage == 1 || flow->l4.udp.hamachi_stage == 2) {
u_int8_t stored_dir = flow->l4.udp.hamachi_stage - 1;
/* Current packet is same direction - verify */
if (dir == stored_dir) {
if (hamachi_l != flow->l4.udp.hamachi_long[dir] ||
hamachi_s != flow->l4.udp.hamachi_short[dir])
{
goto exclude_hamachi;
}
return; /* Still waiting for opposite direction */
}
/* Opposite direction - verify signatures differ */
if (hamachi_l == flow->l4.udp.hamachi_long[stored_dir] ||
hamachi_s == flow->l4.udp.hamachi_short[stored_dir])
{
goto exclude_hamachi;
}
flow->l4.udp.hamachi_long[dir] = hamachi_l;
flow->l4.udp.hamachi_short[dir] = hamachi_s;
flow->l4.udp.hamachi_stage = 3;
return;
}
if (flow->l4.udp.hamachi_stage == 3) {
/* Final consistency check */
if (hamachi_l != flow->l4.udp.hamachi_long[dir] ||
hamachi_s != flow->l4.udp.hamachi_short[dir])
{
goto exclude_hamachi;
}
ndpi_int_hamachi_add_connection(ndpi_struct, flow);
return;
}
exclude_hamachi:
NDPI_EXCLUDE_DISSECTOR(ndpi_struct, flow);
}
static void ndpi_search_hamachi(struct ndpi_detection_module_struct* ndpi_struct, struct ndpi_flow_struct* flow)
{
if(flow->l4_proto == IPPROTO_TCP)
search_hamachi_tcp(ndpi_struct, flow);
else
search_hamachi_udp(ndpi_struct, flow);
}
void init_hamachi_dissector(struct ndpi_detection_module_struct *ndpi_struct)
{
register_dissector("Hamachi", ndpi_struct,
ndpi_search_hamachi,
NDPI_SELECTION_BITMASK_PROTOCOL_V4_V6_TCP_OR_UDP_WITH_PAYLOAD_WITHOUT_RETRANSMISSION,
1, NDPI_PROTOCOL_HAMACHI);
}
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